Disposable absorbent hygiene product with topsheet and acquisition layer

ABSTRACT

A disposable absorbent hygiene product is provided, including a main part having a body facing surface intended to face the body of a user and a garment facing surface intended to face away from the body of a user. The main part includes a liquid permeable topsheet at the body facing surface, a liquid impermeable backsheet at the garment facing surface, and an absorbent assembly arranged between the topsheet and the backsheet. The liquid permeable topsheet material includes a hydrophilically treated polypropylene spunbond nonwoven or spunbond/meltblown composite nonwoven, having a basis weight of from 8 to 20 g/m2. An acquisition layer material is provided sandwiched between said topsheet and said absorbent assembly, being an through air bonded nonwoven.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a national phase entry of, and claims priority to,International Application No. PCT/EP2018/057658, filed Mar. 26, 2018.The above-mentioned patent application is incorporated herein byreference in its entirety.

TECHNICAL FIELD

This application relates to a disposable absorbent hygiene product.

BACKGROUND

Disposable absorbent hygiene products, for example in the form ofdiapers, incontinence garments, pads, inserts and the like, are wellknown. Such articles are used to absorb, distribute and store varioustypes of body exudates, for example urine, while providing a high levelof comfort and sense of dryness to the wearer during use. A conventionaldisposable absorbent product is normally designed with an absorbent corewhich is sandwiched between a topsheet and a backsheet.

General requirements for disposable absorbent hygiene products in thefield of incontinence products is liquid handling and leakage security.As to liquid handling, it is for example important that the products areable to absorb and store liquids while allowing for the skin covered bythe product to be dry, and as to leakage security, it is for exampleimportant that the risk for leakage of body exudates to the outside ofthe product is reduced, as such leakages would be unpleasant to thewearer and lead to soiling of underwear, beds, etc., with an increasedworkload on care givers as a consequence.

There is also a desire to reduce the cost and material spend for theincontinence products. Incontinence products for use by adults, e.g. inelderly care, need to have relatively large physical dimensions tosatisfactory cover the urogenital area of the wearer and to be able tobe properly fitted to the wearer.

Even though approaches taken in the prior art fulfill certainrequirements related to the liquid handling and material spend, there isstill a need for further improvements. To this end, it would bedesirable to improve disposable absorbent hygiene products to overcomethe deficiencies in the art.

SUMMARY

In order to achieve these technical objectives, there is provided adisposable absorbent hygiene product according to embodiments of thepresent invention.

More specifically, the disposable absorbent hygiene product includes amain part having an body facing surface intended to face the body of auser and a garment facing surface intended to face away from the body ofa user, the main part comprising a liquid permeable topsheet at the bodyfacing surface, a liquid impermeable backsheet at the garment facingsurface, and an absorbent assembly arranged between the topsheet and thebacksheet, the main part having a front end and a back end, and defininga longitudinal direction from the front end towards the back end anddefining a transversal direction perpendicular to the longitudinaldirection.

The absorbent assembly is divided by two, imaginary, transversallyextending lines into a front region towards the front end, having alongitudinal length of from 10% to 40% of the absorbent assemblylongitudinal length; a back region towards the back end, having alongitudinal length of from 10% to 40% of the absorbent assemblylongitudinal length; and a central region between the front region andthe back region, where the central region provides from 70% to 100% ofthe total retention capacity of the absorbent assembly.

The liquid permeable topsheet material comprises hydrophilically treatedpolypropylene spunbond nonwoven or spunbond/meltblown compositenonwoven, having a basis weight of from 8 to 20 g/m².

An acquisition layer material is provided sandwiched between thetopsheet and the absorbent assembly, being an air through bondednonwoven having a basis weight of from 40 to 60 g/m² and a caliper of atleast 0.9 mm as measured according to the method NWSP 120.6, option A,and 0.5 kPa pressure.

The product according to the present application has the major part ofthe absorption capacity, in terms of the retention capacity,concentrated to the central portion of the absorbent assembly, meaningthat the absorption capacity is concentrated to the region where it ismost needed. The inventors have found that it may be sufficient toprovide less than 30%, such as from 5% to 20% of the total retentioncapacity in the front and back regions, and that the specificcombination of topsheet material and the acquisition layer materialprovides liquid inlet properties that are advantageous for use with anabsorbent assembly of the specified type where the major portion of theabsorbing capacity is positioned in a central region.

An absorbent assembly according to the present application is theabsorbent assembly per se as defined above.

Further aspects, advantages and advantageous features of the applicationare disclosed in the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention will be appreciated uponreference to the following drawings. The accompanying drawings, whichare incorporated in and constitute a part of this specification,illustrate one or more embodiments of the invention and, together withthe general description given above and the detailed description givenbelow, explain the one or more embodiments of the invention.

FIG. 1 is a top view of a disposable absorbent hygiene product in theform of an open-type diaper.

FIG. 2 is an exploded view of the disposable absorbent hygiene productof FIG. 1.

FIG. 3 is a perspective view of the disposable absorbent hygiene productof FIG. 1 in a closed state.

DETAILED DESCRIPTION

It is to be noted that while the disposable hygiene product in FIG. 1 isillustrated as an open diaper, the present application also relates toother types of disposable absorbent hygiene articles, such as absorbentpads, belted diapers, pant-like diapers and removable inserts.

Different embodiments of the present application will be described morefully hereinafter with reference to the enclosed drawings. Theembodiments disclosed herein can, however, be realized in many differentforms and should not be construed as being limited to the embodimentsset forth herein.

The disposable absorbent hygiene product 1 comprises a main part 10having a body facing surface intended to face the body of a user and agarment facing surface intended to face away from the body of a user,the main part comprising a liquid permeable topsheet 11 at the bodyfacing surface, a liquid impermeable backsheet 12 at the garment facingsurface, and an absorbent assembly 13 arranged between the topsheet andthe backsheet.

In the context of the present application, “disposable” is used in itsordinary sense to mean an article that is disposed or discarded after alimited number of usage events over varying lengths of time, forexample, less than about 10 events, less than about 5 events, or after 1event.

In the disposable absorbent hygiene product illustrated in FIG. 1, thetopsheet 11 and the backsheet 12 extend outside the outer contour of theabsorbent assembly 13 and are joined together outside the absorbentassembly contour using methods commonly known in the art, such as gluingor welding by heat or ultrasound.

The main part 10 has a front end 14 intended to be at the front (belly)waist region of the user, and back end 15 intendent to be at theback-waist region of the user when the product is worn. The main partdefines a longitudinal direction L from the front edge towards the backedge, as well as a transversal direction T perpendicular to thelongitudinal direction.

Longitudinal side edges connect the front edge and the back edge of themain portion on mutually opposite sides of an imaginary longitudinalcenterline C.

A pair of front side panels 21, 22 may each be attached to the main part10 at the longitudinal side edges at or close to the front end thereof.A pair of rear side panels 23, 24 may also be attached to the main part10 at the longitudinal side edges close to the rear end thereof.

The rear side panels 23, 24 may be provided with fastening meansintended to be fastened on the garment facing surface of thecorresponding front side panels 21, 22 or on the garment facing surfaceof the main part 10 in order to fit the disposable absorbent hygieneproduct around the waist of a wearer. The fastening means 25 may forexample be mechanical fasteners, such as hooks, or pressure sensitiveadhesive.

Elastic means 17 that extends in a generally longitudinal manner may beattached to the main part 10, such as sandwiched between the topsheetand the backsheet close to the longitudinal side edges for providing legcuffs, as is commonly known in the art. Such elastic means may compriseone or more elastic threads, elastic film strips or elastic foam strips,and may be attached to the main part 10 in a stretched state in order toexert a longitudinally contracting force on the disposable absorbenthygiene product 1.

Topsheet

A liquid permeable topsheet 11 is arranged at the body-facing side ofthe disposable absorbent hygiene product. Materials suitable astopsheets are commonly known in the art of disposable absorbent hygieneproducts, and for the purposes of the present application any materialcommonly known for use a topsheet materials may be used, including, butnot limited to non-woven materials and perforated polymeric films.

The topsheet 11 is suitably sufficiently fluid permeable to allowdischarged body fluids such as urine to penetrate through the thicknessof the topsheet 11. Also, the topsheet 11 is suitably manufactured froma material which is compliant and soft-feeling to the skin of thewearer.

In the context of the present application, a “nonwoven” is amanufactured sheet, web or batt of directionally or randomly orientatedfibers, bonded by friction, and/or cohesion and/or adhesion, excludingpaper and products which are woven, knitted, tufted, stitch-bondedincorporating binding yarns or filaments, or felted by wet-milling,whether or not additionally needled. The fibers may be of natural orman-made origin and may be staple or continuous filaments or be formedin situ. Commercially available fibers have diameters ranging from lessthan about 0.001 mm to more than about 0.2 mm and they come in severaldifferent forms: short fibers (known as staple, or chopped), continuoussingle fibers (filaments or monofilaments), untwisted bundles ofcontinuous filaments (tow), and twisted bundles of continuous filaments(yarn). Nonwoven fabrics can be formed by many processes such asmeltblowing, spunbonding, solvent spinning, electrospinning, andcarding.

The nonwoven materials to be used for the topsheet 11 may for example bemade of a spunbond, a spunbond/spunbond composite or aspunbond/meltblown composite, such as a SMS(spunbond/meltblown/spunbond), SSMS, SSMMS, SMMS, nonwoven material ofpolypropylene or bicomponent fibers of polypropylene and polyethylene,or of a combination of such materials. The topsheet 11 may also haveelastic properties.

The topsheet 11 is hydrophilically treated in order to improve thetendency for urine to penetrate the topsheet into the underlyingstructures. Methods for hydrophilizing, hydrophilically treating,nonwovens are known to those skilled in the art and include coating thenonwoven material with a hydrophilic coating, such as by applying asurfactant coating; by applying a hydrophilic monomer composition and aradical polymerization initiator onto the nonwoven followed byinitiating a polymerization reaction on the nonwoven; by applying acoating of hydrophilic nanoparticles; or by treating the nonwovensurface with a high energy treatment (corona, plasma).

A surfactant coating may be obtained for example by applying asurfactant composition to the non-woven material by any suitable meansincluding spraying, slot coating, kiss roll coating and/or soaking thematerial in a bath containing the surfactant. The hydrophilizationtreatment may be performed in-line during assembly of the absorbentarticle, or may performed separately and the topsheet may then deliveredas ready-to-use rolls to the disposable absorbent hygiene productmanufacturing plant.

The surfactant coating may be applied to the full width of the topsheetmaterial, or may be limited to a centrally located zone, for examplesuch as to provide a topsheet material with the desired hydrophilicityin the area where it is expected to be directly subjected to body liquiddischarges, while the areas laterally outside the hydrophilized zone mayremain hydrophobic.

Surfactants used for the hydrophilization of the non-woven may be anyknown surfactant suitable for use in hygienic applications, as isgenerally known in the art. Suitable surface-active agents may includeany cationic surfactant, anionic surfactant, nonionic surfactant,zwitterionic surfactant, surfactant of amine oxide type, and siliconebased surfactant suitable for use in hygienic applications and shouldlower the contact angle between the topsheet and urine. Suitablesurfactants also provide a relatively long-lasting hydrophilizationeffect to the non-woven, i.e. they are not readily washed away from thenonwoven, but remains to large extent also after contact with an aqueousliquid, such as urine.

Examples on suitable surface-active agents are; Silastol® PHP26,Silastol® PHP 28, Silastol® 163, Silastol® PHP 207 (products of Schill &Seilacher GmbH of Germany), Stantex® S 6327 (products of Cognis, PulcraChemicals of Germany), Duron™ OS 1547, Duron™ OF 4012 (products ofCHT/BEZEMA of Germany), Nuwet® 237 and Nuwet® 550 (products of MomentivePerformance Materials of New York).

The topsheet (11) has a basis weight of from 8 to 20 g/m², such as from12 to 17 g/m². However, the application is not limited to topsheetmaterials having this basis weight only.

The topsheet material may have a strikethrough time of at most 7, suchas from 1 to 7, for example from 2 to 6 seconds, as measured accordingto the method NWSP (Nonwoven Standard Procedure) 070.3.R0 (15).

An exemplary topsheet is hydrophilically treated polypropylene spunbondor spunbond-meltblown-spunbond nonwoven having a basis weight of from 8to 20 g/m².

Topsheet materials are commercially available for example from Fitesa(Gravitai, Brazil) and Berry Global (Indiana, USA).

Backsheet

A backsheet 12 is arranged at the garment facing side of the disposableabsorbent hygiene product. Materials suitable as backsheets are commonlyknown in the art of disposable absorbent hygiene products. The backsheet12 prevents the exudates absorbed by the absorbent assembly from soilingother external articles that may contact the disposable absorbenthygiene product, such as bedsheets and undergarments. The backsheet 12is substantially impermeable to liquids, such as urine, in oneembodiment.

The backsheet may be substantially liquid impermeable but breathable,i.e. gas permeable, implying that air and other gases may pass throughthe backsheet 12, while being substantially impermeable to liquids.

For the purposes of the present application, any material commonly knownfor use as backsheet materials may be included in the backsheet,including but not limited to polymeric films, for example films ofpolyethylene, polypropylene or copolymers of polyethylene orpolypropylene, hydrophobized nonwoven materials, fluid impermeable foamsand fluid impermeable laminates.

The backsheet may comprise one or more layers of material. For example,the backsheet may be a laminate of a liquid impermeably polymeric filmtowards the absorbent assembly and nonwoven towards the garment side, toprovide a textile, soft feeling to the outer surface of the disposableabsorbent hygiene product.

Absorbent Assembly

An absorbent assembly 13 is arranged between the topsheet 11 and thebacksheet 12. It is here to be noted that an absorbent assembly 13 perse, suitable for use in a disposable absorbent hygiene product,constitutes a separate embodiment of the present application.

The absorbent assembly 13 defines a longitudinal direction from a frontend to a back end, and a transversal direction perpendicular to thelongitudinal direction. In the disposable absorbent hygiene product, theabsorbent assembly is aligned such that the longitudinal direction ofthe assembly is parallel to the longitudinal direction of the disposableabsorbent hygiene product, with the front end of the absorbent assemblytowards the front end of the disposable absorbent hygiene product andwith the back end of the assembly towards the back edge of thedisposable absorbent hygiene product.

The absorbent assembly 13 has a longitudinal length L_(abs) of from 500to 1000 mm, such as from 550 to 750 mm, for example from 570 to 700 mm,and a transversal width W_(abs) of from 200 to 450 mm, such as from 220to 350 mm, for example from 230 to 300 mm.

In the context of the present application, a longitudinal length is tobe understood as the longest length of a specified part or sub part inthe longitudinal direction. Analogously, a transversal width is to beunderstood as the widest width of a specified part or sub part in thetransversal direction.

For the purposes of the present application, and unless otherwiseexplicitly mentioned, lengths, widths and other dimensions of adisposable absorbent hygiene product are measured with the disposableabsorbent hygiene product in a relaxed flattened-out state on a flatsurface with any contracting elastics being deactivated.

The absorbent assembly is divided by two transversally extending,longitudinally spaced apart imaginary lines T1, T2, into (i) a frontregion R_(f) positioned towards the front edge having a longitudinallength of from 10 to 40, such as from 15 to 30, for example from 17 to25% of the absorbent assembly longitudinal length, (ii) a back regionR_(b) positioned towards the back edge having a longitudinal length offrom 10 to 40, such as from 15 to 30, for example from 17 to 25% of theabsorbent assembly longitudinal length, and (iii) a central region R_(c)between said front region and said back region. For avoidance of doubtthe front, central and back regions R_(f), R_(c), R_(b), arenon-overlapping, and together constitute the whole absorbent assembly13.

The planar surface area of the central region R_(c) is significantlysmaller than the planar surface area of the total absorbent assembly.For example, the planar surface area of the central region R_(c) may beat most 75, at most 60, at most 40, or at most 30% of the planar surfacearea of the total absorbent assembly.

As used herein, the term “planar surface area” of the absorbent assemblyor a portion thereof corresponds to the surface area of a flat surfacecovered by (hidden behind) the absorbent assembly or the portion thereofwhen the product is placed on the flat surface in a flattened out statewith any elastics removed or deactivated.

In the front region R_(f) and back region R_(b), the absorbent assemblycomprises a mixture of cellulosic fibers and optionally super absorbentpolymers, with a super absorbent polymer concentration of from 0 to 30,such as from 5 to 20, for example from 8 to 15 weight %, based on thetotal weight of cellulosic fibers and super absorbent articles, and acellulosic fiber basis weight of from 50 to 200, such as from 70 to 170,for example from 100 to 150 g/m².

It may be advantageous that the in the front and back regions, theabsorbent assembly comprises super absorbent polymer, such as in aconcentration of at least 5%, such as from 5 to 20, for example from 8to 15 weight %, in order to provide an absorbent assembly and adisposable absorbent hygiene product having an advantageous balancebetween good liquid handling and material usage.

The mixture of cellulosic fibers and super absorbent polymer may beevenly distributed in the front and the back region of the absorbentassembly, i.e. the cellulosic fiber basis weight and the super absorbentpolymer concentration is essentially consistent over the front and backregions respectively. An evenly distributed mixture of cellulosic fibersand super absorbent polymer in the front and back region allows forthese regions to provide an essentially continuous layer of materialwithout any unintentional openings/material discontinuities.Unintentional openings or material discontinuities may impair the liquidhandling properties and could also lower a user's confidence in theproduct's performance.

In the front and the back region of the absorbent assembly, thecellulosic fibers optionally mixed with super absorbent polymer may havea basis weight coefficient of variation of at most 20%, preferably atmost 15%, more preferably at most 10%, even more preferably at most 5%,as measured according to the method for measuring basis weight evennessprovided in this application.

In the front and the back region of the absorbent assembly, and when thesuper absorbent polymer concentration in these regions is above 5%, themixture of cellulosic fibers and super absorbent polymer may have aretention capacity, calculated as g/g absorbency, with a coefficient ofvariation of at most 20%, preferably at most 15%, more preferably atmost 10%, even more preferably at most 5%, as measured according to themethod for measuring retention capacity evenness provided in thisapplication.

In the front and the back region of the absorbent assembly, and when thesuper absorbent polymer concentration in these regions is above 5%, themixture of cellulosic fibers and super absorbent polymer may have aretention capacity, calculated as g/10 cm² absorbency, with acoefficient of variation of at most 30%, preferably at most 25%, morepreferably at most 20%, even more preferably at most 15%, mostpreferably at most 10%, as measured according to the method formeasuring retention capacity evenness provided in this application.

Further, the central region R_(c) provides from 70 to 100%, such as from75 to 95%, for example from 80 to 90% of the total absorption retentioncapacity of the absorbent assembly, according to the method formeasuring absorption retention capacity as provided in this application.

The retention capacity/planar surface area of the central region R_(c),i.e. the retention capacity of the central region divided by the planarsurface area of the central region, may be significantly higher, such asat least 2 times, at least 3 times, at least 4 times or at least 5 timesthan the retention capacity/planar surface area of the front regionR_(f) and the back region R_(b), respectively. The retentioncapacity/planar surface area of the front region R_(f) and of the backregion R_(b) may be essentially equal, or may differ by less than 20%.

The total absorption capacity of the product, as measured according tothe Rothwell method, ISO 11948, may be at least 1000 ml, such as from1000 to 3000 ml.

The longitudinal length of the front region R_(f) and the back regionR_(b) may be equal or different. For example, the longitudinal length ofthe front region R_(f) may be from 70 to 130%, such as 80 to 120%, or 90to 110% of the longitudinal length of the back region R_(b), to allowfor a tailored positioning of the central region, where the major partof the retention capacity resides, depending on the intended user.

In an absorbent assembly according to the present application, theimaginary lines T1, T2 are positioned such that the longitudinal lengthsof the front and back regions R_(f), R_(b) are maximized, respectively,while meeting the set requirements for the front, central and backregions, R_(f), R_(c), R_(b), respectively. In other words, therequirements for R_(f) and R_(b), that in the front and back regions,the absorbent assembly comprises cellulosic fibers optionally mixed withsuper absorbent polymers, with a super absorbent polymer concentrationof from 0 to 30 weight %, based on the total weight of cellulosic fibersand super absorbent polymer, and a cellulosic fiber basis weight of from50 to 200 g/m², are not fulfilled in any sub portion of R_(c), wheresuch sub portion is defined by two longitudinally separated transverselines.

As illustrated in FIGS. 1 and 2, the absorbent assembly 13 may comprisetwo absorbent cores, a first absorbent core 131 and a second absorbentcore 132 in a stacked relationship, i.e. placed on top of each othersuch that both the longitudinal ends of the second absorbent core arebetween, longitudinally inboard of, the longitudinal ends of the firstabsorbent core. An absorbent assembly based on two absorbent cores instacked relationship provides an advantageous design for a disposableabsorbent hygiene product according to the present application.

First (Big) Core

The first absorbent core 131 may comprise an cellulosic fibersoptionally mixed with super absorbent polymers, with a super absorbentpolymer concentration of from 0 to 30, such as from 5 to 20, for examplefrom 8 to 15 weight %, based on the total weight of cellulosic fibersand super absorbent polymer, and a cellulosic fiber basis weight of from50 to 200, such as from 70 to 170, for example from 100 to 150 g/m². Thefirst absorbent core extends over the full longitudinal length of theabsorbent assembly.

The above-mentioned standard deviation and/or coefficient of variationof the basis weight and/or the super absorbent polymer distribution ofthe front and back regions of the absorbent assembly may also apply tothe full first absorbent core in an embodiment of the invention wherethe absorbent assembly comprises a first and a second absorbent core.

Second (Small) Core

The second absorbent core 132 is positioned in said central region, andthe longitudinal extension of the second absorbent core 132 coincideswith the longitudinal extension of the central region R_(c), such thatthe transversal lines T₁, T₂ coincide with the longitudinally outermostends of the second absorbent core 132.

The second absorbent core 132 may be of any type commonly known assuitable for use in a disposable absorbent hygiene product, for example,absorbent core may be a mixture of cellulosic fibers and super absorbentpolymers, or an essentially cellulose free absorbent structure, such ascontaining up to 100 weight % super absorbent material.

The second absorbent core 132 may for example comprise a mixture ofcellulosic fibers and superabsorbent particles, with a super absorbentpolymer concentration of from 20 to 70, such as from 25 to 50, forexample from 30 to 40 wt % and having a cellulosic fiber basis weight offrom 250 to 500, such as from 300 to 450 g/m².

The planar surface area of the second absorbent core 132 is smaller thanthat of the first absorbent core, for example, it may be less than 75%,such as less than 60% or less than 50%, for example from 40 to 75% ofthat of the first absorbent core 131.

In the embodiment illustrated in FIG. 1, the second absorbent core 132is on the garment facing side of the first absorbent core 131,positioned between the first absorbent core 131 and the backsheet 12. Inalternative embodiments, the second absorbent core 132 may be on thebody facing side of the first absorbent core 131, positioned between thefirst absorbent core 131 and the topsheet 11.

In a disposable absorbent hygiene product in according to the presentapplication where the second absorbent core is positioned between thefirst absorbent core and the backsheet, the first absorbent core maypartly act as a transfer layer for directing fluid away from thetopsheet and into the second absorbent core, where the major portion ofthe liquid retention capacity is concentrated, thereby contributing to agood liquid handling in the product.

The first absorbent core 131 and the second absorbent core 132 may be indirect contact with each other, meaning that there is no additionalmaterial layer, such as a tissue or non-woven core wrap layer, betweenthe two cores.

Core Forming

A core consisting of cellulosic fibers and super absorbent polymer mayin general be produced by different methods known to the person skilledin the art, such as by milling, comminuting, cellulosic material intocellulosic fibers, mixing the fibers with super absorbent polymer,depositing the mixture onto a core forming drum and debulking the corebefore transferring the drum to a substrate, such as a web material ofthe disposable absorbent hygiene product, for example to a topsheetmaterial web or to a backsheet material web. Such cores are commonlyknown as airfelt-based cores. In the absorbent assembly of the presentapplication, at least the front region R_(f) and the back region R_(b),such as the first absorbent core 131 and optionally the second absorbentcore 132 may be airfelt-based, i.e. based on comminuted cellulosicfibers, optionally mixed with super absorbent polymers.

In a core with a low cellulosic fiber basis weight, excessiveflocculation may lead to undesired holes/openings in the core layer thatwill be detrimental to product performance and also to the visualappearance and to the user's tendency to trust the product, thereby thewillingness to use the product.

A high basis weight evenness, i.e. low basis weight coefficient ofvariation, may be achieved by placing the mill very close to the coreforming drum such as to prevent flocculation of the milled fibers in thepathway from the mill to the core forming drum. For a good distributionof the super absorbent polymer, it may be advantageous to add the SAPclose to the mill for achieving a good mixture with the milled fibersprior to deposition on the core forming drum.

Cellulosic materials that can be milled, comminuted, and then used inabsorbent cores according to the present application are well known inthe art and include wood pulp, cotton, flax and peat moss. Wood pulp ispreferred in one embodiment. Pulps can be obtained from mechanical orchemi-mechanical, sulfite, kraft, pulping reject materials, organicsolvent pulps, etc. Both softwood and hardwood species are useful.Softwood pulps are preferred in one embodiment. It is not necessary totreat cellulosic fibers with chemical debonding agents, cross-linkingagents and the like for use in the present material. Some portion of thepulp may be chemically treated for improved flexibility of the product.The flexibility of the material may also be improved by mechanicallyworking the material or tenderizing the material.

Core Positioning

The absorbent assembly may be longitudinally centralized within the mainpart, i.e. the longitudinal distance D_(f) from the front edge of theabsorbent assembly 13 to the front edge of the main part 10 is equal tothe longitudinal distance D_(b) from the back edge of the absorbentassembly 13 to the back edge of the main part 10, or D_(b) may bedifferent from D_(f) to tailor the position of absorption retentioncapacity within the product. For example, the distances D_(f) and D_(b)may independently be from 100 to 300 mm.

As illustrated in FIG. 1, the outer contour of the absorbent assemblymay be hourglass shaped, such that the where the width of the centralregion R_(c) is narrower than the width of the front region R_(f) andthe back region R_(b), respectively, where the width of the back regionand the front region may be equal or different. For example, the backregion may be wider than the front region.

In alternative embodiments, the outer contour of the absorbent assemblymay take different shapes, such as rectangular or oblong.

SAP

Superabsorbent polymers are well-known in the field of absorbentproducts and is used to help improve the absorbent properties of suchproducts. Superabsorbent polymers are constituted by water-swellable andwater-insoluble polymers that are capable of absorbing large quantitiesof fluid upon formation of a hydrogel, such as capable of absorbing atleast 5 times their weight of an aqueous 0.9% saline solution asmeasured according to the method NSWP 241.0.R2 (15). The superabsorbentpolymer polymers for use in accordance with the present application maybe inorganic or organic crosslinked hydrophilic polymers, such aspolyvinyl alcohols, polyethylene oxides, crosslinked starches, guar gum,xanthan gum, crosslinked polyacrylates, and the like. The polymers maybe in the form of powders, granules, microparticles, films, foams andfibers, for example. Upon contact with fluids, such super absorbentpolymers swell by absorbing the fluids into their structures. Ingeneral, super absorbent polymers can quickly absorb fluids insultedinto such articles, and can retain such fluids to prevent leakage andhelp provide a dry feel even after fluid insult.

The type of super absorbent polymer used in an absorbent assembly of thepresent invention may be the same or may vary within the assembly. Forexample, super absorbent polymer with a first set of characteristics maybe used in the front and back regions of the absorbent assembly, or inthe first absorbent core, and super absorbent polymer with a second setof characteristics may be used in the central region of the absorbentassembly, or in the second absorbent core. The characteristics referredto in this section is for example the centrifuge retention capacity(CRC), absorption under load (AUL) and/or the gel layer permeability(GLP).

The first and/or second absorbent core as discussed above may have aneven or a profiled distribution of super absorbent polymer along thethickness of the absorbent core, i.e. along a direction from thebody-facing to the garment facing side of the absorbent core. Forexample, the majority, such as at least 50, for example from 70 to 95 wt% of the super absorbent polymer may be positioned in a middle region,thickness-wise, of the absorbent core. The middle portion may forexample constitute 50% or less, such as from 30 to 50% of the totalthickness of the core, where the middle region is positioned sandwichedbetween a body-facing region and a garment facing region, eachconstituting half of the remainder, thickness-wise, of the absorbentcore, wherein the garment facing region and the body facing regiontogether contain the remainder of the super absorbent polymer amount.The three regions thickness-wise may be clearly distinguishable andeasily separable from each other, or may be integral with each other.

Acquisition Layer

According to the present application, a disposable absorbent hygieneproduct comprises an acquisition layer 16 arranged between the topsheet11 and the absorbent assembly 13.

As illustrated in FIG. 1, such acquisition layer 16 may be arrangedsandwiched between the topsheet 11 and the absorbent assembly 13, on topof the central region R_(c) of the absorbent assembly. The acquisitionlayer may be at least partially within, such as wholly within thecentral region R_(c). For example, the contour of the acquisition layer16 may be fully within the contour of the second absorbent core 132,when viewed from the top with the product in a flattened-out state on aplanar surface.

While an absorbent assembly of the present application is intended toreceive and hold large amounts of exudates, such as urine, it may beadvantageous to include an acquisition layer between the topsheet andthe absorbent assembly provide for interim acquisition of large amountsof liquid, as well as providing a layer for the distribution of liquidaway from the immediate place of impact.

The acquisition layer in accordance with the present application is athrough air bonded nonwoven having a basis weight of from 40 to 60 g/m²and a caliper of at least 0.9 mm as measured according to the methodMWSP 120.6, option A, at 0.5 kPa pressure.

The acquisition layer may have a sufficiently high caliper before thearticle is used, but also maintain a high caliper even in use conditionswhen the article is subject to external pressure. The acquisition layerhas a caliper of at least 0.9 mm, such as from 0.9 to 2 mm, for examplefrom 1 to 1.5 mm, at a pressure of 0.5 kPa as measured according to themethod NWSP 120.6.R0 (15), method option A.

One exemplary acquisition material is commercially available from BerryItaly under the tradename B5, and is a through-air bonded nonwovenhaving a basis weight of 40-60 g/m² and a caliper of about 1 mm,comprising a mixture of about 50 weight % polyester fibres and theremainder of the fibers being bi-component fibers of polyester.

The acquisition material may comprise a blend of different fibers, suchas a blend of two or more types of fibers. Such blend may comprise atleast 10, 20, 30, 40, 50, 60, 70, 80, or 90 weight % of a first type andthe remaining weight % portion of other types of fiber types of fibersand optionally further components, such as binders, such as latex. Thefibers of the acquisition layer may comprise or consist of polyester.For example, the blend may comprise from 40 to 60 weight % of a firsttype of fiber, and from 30 to 60 weight % of a second type of fiber. Theacquisition layer may optionally comprise up to 30 weight %, morepreferably up to 20 weight % of additional components.

The first type of fiber may be a fiber exhibiting a spiral-crimp,preferably from polyester in one embodiment. As used herein, aspiral-crimp is any three-dimensional crimp, for example one wherein thefibers substantially assume a helical shape. The spiral-crimp fiber mayconsist of or comprise hollow fibers, i.e. a fiber whose cross-sectionalarea is hollow, such as 10 to 30%, for example 15 to 20% of the crosssectional area is hollow.

The second fiber may comprise or consist of a polyester bi-componentfiber, such as a core-sheath fiber with a lower melting temperaturematerial in the sheath and a higher melting temperature material in thecore.

In the blend, the second type of fibers may be thinner than the firsttype of fibers. The second type of fibers may have 3-9, such as 5-8, forexample 6-7 dtex. The first type of fibers may have 8-12, such as 9-10dtex. The first type of fibers and the second type of fibers may be ofdifferent length, or of the same length. The fibers may have an averagelength from 20 to 70 mm, such as from 30 to 50 mm.

Acquisition materials of through-air bonded nonwovens comprising spiralcrimp fibers of polyester and polyester bi-component fibers aregenerally disclosed in International patent Application Publication No.WO99/00098 to SCA Hygiene Products AB, the contents of which is includedherein by reference.

Without wishing to be bound by theory, it is further believed that thespiral crimping of fibers is very beneficial for their liquidacquisition and distribution behavior. It is assumed that the spiralcrimp increases the void space in an acquisition member formed by suchfibers. Often, an absorbent article, when being worn, is exposed to acertain pressure exerted by the wearer, which potentially decreases thevoid space in the acquisition member. Having good permeability andsufficient void space available are desirable for good liquiddistribution and transport. It is further believed that thespiral-crimped fibers as described above are very suitable to maintainsufficient void volume even when an acquisition member is exposed topressure. In addition, spiral-crimped fibers believed to provide forgood permeability as for a given fiber dtex value, and a hollow fibercross-section allows for a larger outer diameter of the fiber ascompared to a compact cross-section. The outer diameter of a fiberappears to determine the permeability behavior of an acquisition memberformed by such fibers.

Additional Components

Further components commonly employed in disposable absorbent hygieneproducts but not illustrated in the figures of the present applicationmay be employed in a disposable absorbent hygiene product according tothe present application.

For example, raised elastic members, commonly known as standing gathers,may be attached to the topsheet.

A wetness indicator, for example a material that changes its color uponcontact with urine, may be included in the disposable absorbent hygieneproduct, such as disposed between the absorbent assembly and thebacksheet and visible through the backsheet, such as to indicate whethera wetting event has taken place.

Moreover, when the disposable absorbent hygiene product is anincontinence pad, a fastening means, such as a strip of pressuresensitive adhesive, may be disposed on the garment facing side of thebacksheet to provide secure placement of the pad in the underwear.

Methods Method for Measuring Basis Weight Evenness

For the evaluation, take five adjacent diapers from one and the sameconsumer package, or take five consecutively produced diapers fromproduction.

Unfold the diapers if folded, and lay bare for 48 hours in a stablelaboratory environment set to 23° C. and 50% relative humidity. Testingis performed in this same environment.

Remove or neutralize all elastic elements in the diaper, and place thediaper smooth and flat. Samples for evenness evaluation are then punchedout from the diaper. The punching tool has outer dimensions of 50×120mm, with cutting cross bars every 20 mm. The tool thus cuts 6 adjacentsamples, each sample measuring 50×20 mm (10 cm²). Two sets of 6individual samples (12 samples in all) are cut from each diaper.Referring to FIG. 3, one set of six samples is taken from the frontregion (R_(f)), and the other from the back region (R_(b)). The punchingtool should be placed immediately outside the central region (R_(e)).The tool's length dimension coincides with the diaper's transversedirection. The punching tool should be centered on the diaper'slongitudinal centerline (C).

Determine the weight (to the nearest milligram) of each 50×20 mm coresample. For this purpose, any additional layers (such as the topsheet orthe backsheet) first should be subtracted. Take care so that nosuperabsorbent or significant amounts of fibers are lost when layingbare the core. Alternatively, the punched sample can be weighed as is.The basis weight of the additional layers then should be knownbeforehand (from the material specification or a separatedetermination), so that their weight can be subtracted from the samples.

Calculate the basis weight (g/m²) for each sample from the large core:

(Sample weight (g))/(Sample area(0.001 m²))

Calculate the (arithmetic) mean basis weight (g/m²) for the series of 60samples, and then calculate the standard deviation for the series:

$\delta = \sqrt{\frac{\sum_{i = 1}^{N}\left( {x_{i} - \overset{\_}{x}} \right)^{2}}{N - 1}}$

where x is the basis weight of the individual sample, x is thearithmetic mean, and N is the number of samples (count 60).

Finally calculate the coefficient of variation (CV) by dividing thestandard deviation by the mean. Express the ratio in percent (%).

Method for Measuring Evenness of Retention Capacity

This test evaluates the evenness of the retention capacity in the frontand back regions of the absorbent assembly, an indicates thedistribution of superabsorbent polymer. For this purpose, make use ofthe same 60 samples that were used in the Basis Weight Evenness test(described above).

As a conventional superabsorbent polymer absorbs way more thancellulosic fibers, a suitable test method has been found in the CRC-test(Centrifuge Retention Capacity). The method is well known in theindustry, and is available from EDANA or INDA under the full nameStandard Procedure: NWSP 241.0.R2 (15), entitled “PolyacrylateSuperabsorbent Powders—Determination of the Fluid Retention Capacity inSaline Solution by Gravimetric Measurement Following Centrifugation”.

A sample is placed in a sealable nonwoven bag, and the sample is thenimmersed in a 0.9% NaCl solution for 30 minutes. The sample isthereafter centrifugated in a 250 g-force to remove interstitial fluid,after which g/g absorbency and g/sample absorbency, i.e. g/10 cm²absorbency is determined.

g/g absorbency=(final sample weight−initial sample weight)/initialsample weight

g/10 cm² absorbency=final sample weight−initial sample weight

The skilled person can easily adopt the test to a 20×50 mm excision fromthe core. However, note that larger nonwoven bags should be used toaccommodate the larger core samples. Only the core components(conventionally the cellulose pulp and the superabsorbent) are includedin the g/g absorbency calculation. Any additional layers (such astopsheet or backsheet) only can be included with the core sample if theyare substantially non-absorbent (such as polyolefin or polyester filmsor fibers), and their dry weight should then be subtracted in all sampleweight determinations. Additional layers containing absorbent material(such as viscose or cotton fibers) should be removed before testing.

Calculate Coefficient of Variation (CV) for the g/g absorbency and g/10cm² in the series of 60 samples from the core. The calculation principleis the same as in the Basis Weight Evenness test

Total Retention Capacity of the Absorbent Assembly

Retention capacity of the absorbent assembly can easily be evaluatedalong the principles of the CRC-test (Centrifuge Retention Capacity).This method is well known in the industry, and is available from EDANAor INDA under the full name Standard Procedure: NWSP 241.0.R2 (15).Polyacrylate Superabsorbent Powders—Determination of the Fluid RetentionCapacity in Saline Solution by Gravimetric Measurement FollowingCentrifugation. However, the test is designed for small samples, andsome modifications are performed for evaluating a whole absorbentassembly as described below.

Diapers for testing are removed from their package, unfolded, and laidbare for 48 hours in a stable laboratory environment set to 23° C. and50% relative humidity. Testing is performed in this same environment.

Isolate the absorbent assembly, using a pair of scissors or a scalpel.Take care so that no superabsorbent particles escape. Weigh theassembly, and then place it in a pouch made of a nonwoven or woven web(suitable web properties are described in the standard NWSP 241.0.R2).Then seal the pouch using a heat sealer. (In case the absorbent assemblyis unpractically big it can of course be split in smaller parts, whoserespective absorbencies are then added up.) Submerge the pouch in 3liters of 0.9% NaCl solution (change solution for each individualsample), and let it absorb for 30 minutes. Then centrifuge the assemblyfor 3 minutes in a 250 g force. Finally subtract the weight of the dryassembly and the pouch. The amount of saline solution thus retainedsignifies the total retention capacity of the absorbent assembly.

The test can also be performed on the central region (R_(c)) alone, orother relevant regions. In this case the region is carefully cut looseusing a pair of scissors or a scalpel. For comparing the central region(R_(c)) capacity to the capacity of the whole absorbent assembly, use 10representative diapers for each retention determination, and calculatethe ratio (in percent) between the respective arithmetic means.

EXAMPLES

Two liquid acquisition properties, the Rate of Acquisition (ROA) andrewet, for two different adult open diapers were evaluated according tothe methods described in NSWP 070.9.R1 (15).

Product 1 was according to the present disclosure, as illustrated inFIG. 1, with a topsheet being a hydrophilically treated 15 g/m² spunbondnonwoven commercially available as B0305-5 from Berry® North America,and the acquisition layer material being a through air bonded polyesterbased nonwoven having a basis weight of about 50 g/m² and a caliper ofabout 1 mm, commercially available as B5 from Berry® Italy.

Product 2 was according to the same specifications, except for theacquisition layer material being exchanged to an apertured film with abasis weight of 26 g/m² commercially available as AquiDry Plus®120-35490 from Tredegar Film Products, of Virginia, USA and accordinglynot according to the present disclosure.

The results of the tests were as follows:

ROA (average of 5) Rewet (average of 5) Product 1 47.60 s 0.09 g Product2 (reference) 65.20 s 0.12 g

As can be seen from this result, the combination of topsheet andacquisition layer material in accordance with the present disclosureprovides a quicker acquisition rate and a lower rewet compared to thereference.

The embodiments described above are only descriptions of preferredembodiments of the present invention, and are not intended to limit thescope of the present invention. Various variations and modifications canbe made to the technical solution of the present invention by those ofordinary skill in the art, without departing from the design and spiritof the present invention. The variations and modifications should allfall within the claimed scope defined by the claims of the presentinvention.

What is claimed is:
 1. A disposable absorbent hygiene productcomprising: a main part having a body facing surface intended to face abody of a user and a garment facing surface intended to face away fromthe body of a user, the main part comprising a liquid permeable topsheetat the body facing surface, a liquid impermeable backsheet at thegarment facing surface, and an absorbent assembly arranged between thetopsheet and the backsheet, the main part having a front end and a backend, and defining a longitudinal direction from said front end towardssaid back end and defining a transversal direction perpendicular to thelongitudinal direction, wherein the absorbent assembly is divided bytwo, imaginary, transversally extending lines into a front regiontowards said front end, having a longitudinal length of from 10% to 40%of a longitudinal length of the absorbent assembly; a back regiontowards said back end, having a longitudinal length of from 10% to 40%of the longitudinal length of the absorbent assembly; and a centralregion between said front region and said back region, wherein in thefront and back regions, the absorbent assembly comprises cellulosicfibers mixed with super absorbent polymers, with a super absorbentpolymer concentration of from 0 to 30 weight %, based on a total weightof cellulosic fibers and super absorbent polymer, and a cellulosic fiberbasis weight of from 50 to 200 g/m²; wherein said central regionprovides from 70% to 100% of a total retention capacity of the absorbentassembly, wherein the liquid permeable topsheet comprises at least oneof a hydrophilically treated polypropylene spunbond nonwoven andspunbond/meltblown composite nonwoven, having a basis weight of from 8to 20 g/m²; and wherein an acquisition layer material is providedsandwiched between said topsheet and said absorbent assembly, being anthrough air bonded nonwoven having a basis weight of from 40 to 60 g/m²and a caliper of at least 0.9 mm as measured according the method NWSP120.6, option A, at 0.5 kPa pressure.
 2. The product according to claim1, wherein said acquisition layer material comprises polyester fibers.3. The product according to claim 1, wherein said acquisition layermaterial comprises a blend of two or more types of fibers, wherein from40 to 60 weight %, based on a total weight of the acquisition layermaterial, is polyester spiral crimp fiber, and wherein from 30 to 60weight %, based on the total weight of the acquisition layer material,is polyester bicomponent fiber.
 4. The product according to claim 3,wherein said polyester spiral crimp fiber comprises hollow spiral crimpfiber.
 5. The product according to claim 1, wherein said acquisitionlayer material is wholly positioned within an area of said centralregion.
 6. The product according to claim 1, wherein said topsheet ishydrophilically treated by a surfactant coating.
 7. The productaccording to claim 1, wherein said topsheet has a strikethrough time ofat most 7 seconds, as measured according to NSWP070.3.R0 (15).
 8. Theproduct according to claim 1, wherein said absorbent assembly comprisesa first absorbent core having cellulosic fibers, mixed with superabsorbent polymers, with a super absorbent polymer concentration of from0 to 30 wt %, and having a cellulosic fiber basis weight of from 50 to200 g/m², said first absorbent core extending over a full longitudinallength of the absorbent assembly, and a second absorbent core positionedin said central region and in stacked relationship with said firstabsorbent core.
 9. The product according to claim 8, wherein saidacquisition layer material is wholly positioned within an area of saidsecond absorbent core.
 10. The product according to claim 8, whereinsaid second absorbent core is positioned between said first absorbentcore and at least one of said backsheet and said topsheet.
 11. Theproduct according to claim 8, wherein a super absorbent polymerconcentration in said first absorbent core is at least 5 weight %. 12.The product according to claim 8, wherein said second absorbent corecomprises a mixture of cellulosic fibers and super absorbent polymer,with a super absorbent polymer concentration of from 20% to 70% andhaving a cellulosic fiber basis weight of from 250 to 500 g/m².
 13. Theproduct according to claim 1, wherein said absorbent assembly has alongitudinal length of from 500 to 1000 mm and a transversal width offrom 200 to 450 mm.
 14. The product according to claim 2, wherein saidacquisition layer material comprises a blend of two or more types offibers, wherein from 40 to 60 weight %, based on a total weight of theacquisition layer material, is polyester spiral crimp fiber, and whereinfrom 30 to 60 weight %, based on the total weight of the acquisitionlayer material, is polyester bicomponent fiber, wherein said polyesterspiral crimp fiber comprises hollow spiral crimp fiber, wherein saidacquisition layer material is wholly positioned within an area of saidcentral region, wherein said topsheet is hydrophilically treated by asurfactant coating, wherein said topsheet has a strikethrough time of atmost 7 seconds, as measured according to NSWP070.3.R0 (15), wherein saidabsorbent assembly comprises a first absorbent core having cellulosicfibers, mixed with super absorbent polymers, with a super absorbentpolymer concentration of from 0 to 30 wt %, and having a cellulosicfiber basis weight of from 50 to 200 g/m², said first absorbent coreextending over a full longitudinal length of the absorbent assembly, anda second absorbent core positioned in said central region and in stackedrelationship with said first absorbent core, wherein said acquisitionlayer material is wholly positioned within an area of said secondabsorbent core, wherein said second absorbent core is positioned betweensaid first absorbent core and at least one of said backsheet and saidtopsheet, wherein a super absorbent polymer concentration in said firstabsorbent core is at least 5 weight %, wherein said second absorbentcore comprises a mixture of cellulosic fibers and super absorbentpolymer, with a super absorbent polymer concentration of from 20% to 70%and having a cellulosic fiber basis weight of from 250 to 500 g/m²,wherein said absorbent assembly has a longitudinal length of from 500 to1000 mm and a transversal width of from 200 to 450 mm.